Conventional bar codes have varying width bars and spaces suitably printed on a label. The bar code may take any conventional form in one or more dimensions, and includes, for example, the typical one-dimensional UPC form. The UPC symbology is based on a specification enacted by the Uniform Product Code Council, Inc. of Dayton Ohio. The typical UPC bar code includes a series or sequence of alternating dark bars and light spaces of varying widths. The bars and spaces are arranged in groups representing individual characters. The bar code starts with a left margin character and ends with a right margin character, and has a center reference character as well, with the characters provided there between representing any desired data.
The minimum width of either a bar or space in the UPC symbology is defined as a single module, which represents a unit width. The width of a single character coded using the UPC symbology is seven (7) modules. A seven module UPC character has two bar and two space elements which have varying widths to differentiate between the respective characters.
Prior art single window bar code scanners have laser scan patterns that are typically optimized to perform either in a horizontal mode for bottom and leading edge reading, or in a vertical mode of operation for top down or side reading. Horizontal scanners perform well when used in the horizontal mode, however they generally perform poorly when operated in a vertical mode and vise versa. Some prior art scanners, such as the NCR 7882 model horizontal scanner, have a pattern optimizer able to adjust a portion of the scan pattern for use in the vertical scan mode. In the NCR 7882 the optimizer affects the horizontal and diagonal scan lines, but does not affect the vertical lines. Accordingly, the scanner is not fully optimized for use in both horizontal and vertical modes.
It is an object of the present invention to produce a bar code scanner, which obviates the problems discussed above.